The severity of the reduction in renal function in each subject will be classified according to the glomerular filtration rate (GFR) estimated using the Japanese GFR estimation equation. Subjects will start with a screening period, followed by a single-blind placebo run-in period, and will be randomized to the ASP1941 groups or the placebo group at a ratio of 2:1. For randomization, subjects will be stratified according to the severity of the reduction in renal function. In a treatment period, subject will receive study drug or placebo for 24 weeks under double-blind conditions.